Mr. Yang, believed to be a deranged serial killer, tormented Shawn (James Roday) and Gus over three seasons. In Sheedy’s last appearance, “Psych’s” fifth-season finale, it was revealed that she was only assisting the real killer — her father, Mr. Yin (Peter Weller).

We can’t begin to imagine how Yang will be involved the musical episode. Sheedy joins previously announced guest starsBarry Bostwick, who plays the womanizing owner of the theater staging a musical production (which we believe is called “Ripper!”), Brooke Lyons and Anthony Rapp.